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# Organic Chemistry Practice Problems

Organic chemistry is a subject that blends basic chemistry. Organic chemistry covers a pretty large amount of material is a bit like saying that oxygen is pretty important for human survival. Mastering organic chemistry without working problems is impossible, kind of like becoming an architect without bothering to draw up any plans.

There is no surer way to learn organic chemistry than by working problems. Although careful reading and rereading of text are important, reading alone isn't enough. Early problems are primarily of the drill type, providing an opportunity for practicing the fundamentals. Later problems tend to be more thought-provoking and some are real challenges.

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## Organic Chemistry Practice Problems with Answers

A sample of gaseous hydrocarbon occupying 1.12 liters at N.T.P when completely burnt in air produced 2.2 of CO2 and 1.8g of H2O. Calculate the weight of the compound taken and the volume of oxygen at N.T.P required for its burning. Find the molecular formula of the hydrocarbon.

### Solution

Weight of CO2 = 2.2g
Weight of carbon = $\frac{2.2}{44}$ x 12 = 0.8g
Weight of water = 1.8g
Weight of H = $\frac{10}{18}$ x 1 = 0.2g
Atomic ratio : C:H = $\frac{0.6}{12}$ : $\frac{0.2}{1}$ = 1.4
Therefore empirical formula is CH4
Weight of the hydrocarbon : 0.6 + 0.2 = 0.8g

In 22.4l (1 molar volume) the hydrocarbon is $\frac{0.8}{0.12}$ x 22.4 or 16g
Weight of 1 mole of the hydrocarbon = 16g

Molecular formula is CH4

Moles of oxygen required for C = $\frac{0.6}{12}$ and for H = $\frac{0.2}{2}$

Total oxygen required = 0.05 + 0.05 = 0.1 mole.

## Organic Chemistry Nomenclature Practice Problems

Write the IUPAC rules for naming compounds containing functional groups

### Solution

The following rules may be considered in naming compounds containing one functional group.
1. The name of a compound containing a single functional group is obtained by adding a suffix to the root derived from the name of the hydrocarbon of longest carbon chain. This suffix replaces the ending -ane.
2. The chain is so numbered that the functional group always gets the lowest number.
3. A functional group containing a C-atom is always assigned position 1 and its location is not mentioned while writing the name of the compound.

Examples

 5-Methylhex-1-ene(letter e is retained in terminal -ene because of its terminal position) 2-Pentanone (pent-2-one) 4-Methylpentanoic acid Ethyl3,3-dimethylbutanoate N,N-dimethylpropanamine(N,N-dimethyl-1-aminopropane is wrong) 2-Methyl-3-hexanamine N-Methyl-4-pentenamine

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